Some disconnected thoughts on this:
-Quest giver could be post-AoLS Khelevaster in Terinyo--another NPC would be fine, but he's already there and it fits well with lore.
-Platinum girdle is an obvious candidate for an order hero item. It's so obscenely hard to get in 1.2.0, so having it be of some importance could work.
-Khelevaster could require you to "purify" the Chaos Trinity items somehow. If you speak to him crowned L+, then he will reveal the location of the ancient stone circle, then perform some sort of ritual to transform it in to its original "lawful" form. I was thinking something to the effect of: Visit the volcano and mine some volcanic stone. Smelt into volcanic ingots, then dip each into into a PoCC to create some platinum ingots. Smith the Crown of Chaos in Darkforge using holy ingots to create the Crown of Order. The quest should probably require a sacrifice on par with 6 artifacts. Maybe a specific artifact pickaxe (Rolf's?), anvil or hammer would be required to process the ores properly as well.
-ToTRR can be acquired in the usual way, I suppose.
Hoping to win with every class, doomed. Archer, Barbarian, Bard, Beastfighter, Druid, Elementalist, Farmer, Fighter, Monk, and ULE Priest down.